“Love and Capital: Karl and Jenny Marx and the Birth of a Revolution” (Little, Brown and Co.), by Mary Gabriel

Karl Marx, the father of international communism, was a devoted husband to his wife, Jenny, a daughter of Prussian and British aristocracy.

In the newest Marx biography, “Love and Capital,” author Mary Gabriel writes that she had been unable to find one “that told the bittersweet drama that was their life story. At the depth of the couple’s long poverty, Jenny still carried calling cards identifying her as “born, Baroness Jenny von Westphalen.”

The couple had seven children, but only three lived to adulthood. Two daughters who grew up killed themselves because of political and marital problems.

Friedrich Engels, a close friend, collaborator and financial supporter of Marx, spoke for the ailing husband at Jenny’s funeral.

“The contribution made by this woman,” he said, “with such a sharp critical intelligence, with such political tact, a character of such energy and passion, with such dedication to her comrades in the struggle — her contribution to the movement over almost 40 years has not become public knowledge ...”

Jenny, 22, secretly became engaged to 18-year-old Karl in 1836 as he was entering university. In Berlin he wrote three books of poetry for her, a 300-page philosophy of law, translations from Greek and Roman edicts, history and poetry, and a comic novel and a play.

When they finally overcome family objections sufficiently for them to wed, the 45 books the bridegroom took along to study on their honeymoon resulted in two of his best-known conclusions: Religion is the opium of the people and the proletariat, the lowest class in society, is the heart of mankind’s emancipation.

Some readers may be wearied by the author’s meticulous account of how the couple pawned, begged and borrowed from family, friends and colleagues over the next 25 years; their expulsions by hostile governments; their slum dwellings; and their surrounding misery.

But those interested in European political development of the 19th and 20th centuries will be fascinated by the story of the monocled, bearded, poverty-stricken lecturer on economics and his small, powerless audiences of refugees.

Under the influence of Marx and Engels, a secret group in France called the League of the Just gradually became the Communist League. It changed its slogan of “All Men Are Brothers” to “Working Men of All Countries, Unite!”

The process underlined the contention of Marx and Engels that the revolution should be an international uprising, not a national affair, as it became in Russia. When their small book appeared, it was titled, “The Manifesto of the Communist Party.” Today it’s known as the Communist Manifesto.

The couple’s living standard improved after the Franco-Prussian War of 1870, when Karl published a book on the civil conflict that followed in France. The first volume of his economic masterpiece, “Capital,” also began to appear.

Marx became the leading light of the Communist League, known later as the First International. It eventually collapsed as did its three successors.